In a typical cellular wireless communication system, an area is divided into cells and cell sectors, each defined by a radiation pattern (on a particular frequency) from a respective base station or “base transceiver station”. Each base station is then typically connected with core network equipment that functions to provide connectivity with a transport network such as the public switched telephone network (PSTN) or the Internet for instance, and that may function to control base station operation and handoff of served client devices from one base station to another. Such equipment may include a controller referred to as a base station controller (BSC) or a radio network controller (RNC). Further, the controller may be coupled with a switch that connects with the PTSN and/or a gateway such as a packet data serving node (PDSN) that connects with a packet-switched network such as the Internet. Conveniently with this arrangement, a cell phone or other wireless client device (generally “mobile station”) that is positioned within the coverage area of a given sector can communicate over an air interface with the base station and in turn via the core network equipment with entities on the transport network.
Mobile stations and base stations generally communicate with each other over a radio frequency (RF) air interface according to a defined air interface protocol, examples of which include CDMA (e.g., IS-95, IS-2000, 1xRTT, 1xEV-DO, etc.), iDEN, WiMAX, TDMA, AMPS, GSM, GPRS, UMTS, EDGE, LTE, WI-FI (e.g., 802.11), BLUETOOTH, and others now known or later developed. Such air interface communication typically occurs on a frequency known as a “carrier” (which may actually be a pair of frequencies, one for communications from the base station to the mobile station, and another for communication from the mobile station to the base station). On such a carrier, the base station may emit a pilot signal, which is a control signal that a mobile station may detect as an indication of base station coverage. In particular, as the mobile station moves into the coverage of a base station and is operating on the base station's carrier, the mobile station may detect the base station's pilot signal. In response, the mobile station may then hand off to operate in the indicated coverage area.
A wireless service provider typically operates numerous base stations in a given geographic region, to provide robust air interface coverage as mobile stations move from one location to another. These cellular base stations are usually not associated with any subscriber or small group of subscribers in particular; rather, they are usually placed in publicly-accessible locations designed so that their coverage blankets cities, rural areas, etc. to be used by the service provider's customers generally. As such, these types of base stations are generally known as “macro base stations,” and the network that they collectively form, or to which they belong, is generally known as a “macro network.”
Many macro-network subscribers, including private consumers and small businesses, among others, in addition to having wireless service (which may include data service) for their mobile station(s), may also have high-speed (“broadband”) Internet access through another communication channel. This other channel may be cable-modem service, digital-subscriber-line (DSL) service, satellite-based Internet service, and/or some other type of connection. In an exemplary arrangement, a user may have a cable modem connected (a) via coaxial cable to the cable provider's network and (b) via Ethernet cable to a wireless (e.g. IEEE 802.11 (WiFi)) router. That router may include one or more Ethernet ports to which computers or other devices may be connected, and may also include wireless-access-point functionality, providing a WiFi packet-data interface to devices such as laptop computers, digital video recorders (DVRs), appliances, and/or any other computing devices or their wireless network adapters.
To address gaps in macro-network coverage (e.g. poor in-building coverage) and for other reasons, macro-network providers may offer their subscribers private base station devices known as “femtocells,” (also sometimes referred to as picocells, ubicells, microcells, or as femto-, pico-, ubi-, or micro-base stations or base transceiver stations), which are essentially small, low-power, low-capacity, and low-cost versions of a macro base station. As a general matter, a femtocell, which may be approximately the size of a desktop phone or WiFi access point, may communicate (through a wired or wireless link) with the user's broadband router and may establish a virtual private network (VPN) connection via the Internet with the wireless service provider's core network (e.g., with a femtocell controller on the wireless service provider's network). Further, the femtocell may include a wireless communication interface that is compatible with the user's mobile stations and that is arranged to serve the mobile station in much the same way that a macro base station does, providing a pilot signal and so forth. With a femtocell positioned in a location where macro network coverage may be poor or unavailable, a user's mobile station can thus be served by the femtocell in much the same way that the mobile station would be served by a macro base station when within coverage of the macro network.
To avoid interference with macro network communication, a femtocell may operate on a different carrier than that used by macro base stations. Further, to facilitate handoff of mobile stations from the macro network to a femtocell, the femtocell may emit a pilot “beacon” on the carrier frequency of the nearby macro network. The pilot beacon includes administrative messages and parameters that mobile stations can use to connect with the femtocell and thus serves to inform a mobile station that the mobile station may begin scanning for coverage on the carrier of the femtocell. Thus, when a mobile station is operating in the macro network and approaches the coverage of a femtocell, the mobile station may detect the femtocell's pilot beacon and responsively begin scanning the femtocell's carrier in search of a pilot signal to facilitate handoff to the femtocell.
A typical femtocell also includes a Global Positioning System (GPS) receiver for use in receiving and decoding GPS satellite signals. GPS signals may be used in a well known manner to determine the location of the femtocell, and the GPS-determined location of the femtocell may be used as a basis to authorize operation of the femtocell. In particular, upon startup, the femtocell may report its location via the broadband connection to the wireless service provider's core network, and an entity on the wireless service provider's network may determine whether the femtocell is allowed to operate at that location. If so, the entity may allow the femtocell to operate. Or if not, the entity may block operation of the femtocell.